1. Field of the Invention
This invention relates to image processing apparatus for processing predetermined images as more particularly to an endoscope image processing apparatus for processing images obtained by an endoscope inserted into a body cavity to non-invasively diagnose affected parts.
2. Related Art Statement
Recently an endoscope, which can insert an elongate insertable part into a body cavity to observe organs within the body cavity or, as required, can make various therapeutic treatments using a treating instrument inserted through a treating instrument channel, has been extensively utilized.
Various electronic endoscopes have been suggested using an imaging means such as a solid state imaging device as a charge coupled device (CCD).
An example of a conventional endoscope apparatus is shown in FIG. 26. As shown in this drawing, a light emitted from a lamp 31 is time-serially separated into the respective wavelength regions of R (red), G (green) and B (blue) by a rotary filter 33 having filters 33R, 33G and 33B transmitting the light of the respective wavelength regions of red (R), green (G) and blue (B) and rotated by a motor 33 and is emitted into an endoscope light guide 23 at the entrance end. This frame sequential illuminating light is led to the endoscope tip part by the above mentioned light guide 23, is emitted from this tip part and is radiated onto an object to be imaged. The returning light from the object by this illuminating light is made to form an image on a CCD 41 provided in the endoscope tip part 9 by an image forming optical system 22. An image signal from this CCD 41 is amplified to be on a voltage level in a predetermined range by an amplifier 42. The output of this amplifier 42 has .gamma. corrected by a .gamma.-correcting circuit 43, is then converted into a digital signal by an A/D converter 44 and is stored in respective memories 46R, 46G and 46B through a switching switch 45. The image signals stored in the respective memories are read out by the timing of television signals and are converted into analog signals respectively by D/A converters 47R, 47G and 47B. These analog image signals together with a synchronizing signal SYNC from a synchronizing signal generating circuit 52 are transmitted to RGB signal output ends 49R, 49G and 49B. The thus obtained RGB signals are displayed on a monitor to make an endoscope observation. The above mentioned synchronizing signal is output from a synchronizing signal output end 49S and is input together with the RGB signals into the monitor.
Recently, various image processes are made for such an endoscope apparatus. As examples of such an image process, there are a) a coloration enhancing process whereby three RGB signals are converted to be in uniform color spaces of the brightness, chroma and hue and are processed to be enhanced as is shown in the publication of Japanese Patent Application Laid Open No. 173182/1988 and b) an operating process whereby a part of three RGB signals is changed to be in an infrared region and the oxygen saturated degree in the living body tissue is determined by an operation between pixels as is mentioned in U.S. Pat. No. 4,878,113.
However, in the conventional image process, the entire picture is uniformly processed. That is, regions which are not in proper exposure ranges such as a halation part and shadow part and even a region in which no effective precision is obtained due to the capacity and unit drop of the operating process means in the operating process are displayed as processed. Therefore, the region which is reliable in the processed image and the the region which is not reliable are difficult to discriminate from each other and have caused misconception.